So near and yet so far...
Haven't been very active round here recently so catching up on things...
Last couple of weeks I've been attempting to tune the room prior to starting on the final cosmetic jobs. I've made at least 200 ETF measurements and have the speakers now in their optimum position. When I say "optimum", I of course mean "compromise" because in my type of room, there isn't a perfect solution.
Anyway, during all this testing, I once hit upon a magic spot but as I was between tests, I lost the speaker position and haven't been able to get it back, despite taking accurate measurements. Strange that it should appear to be so sensitive to position when that position is less than one inch in each direction (two inches if you add up error on both monitors).
Having lost the sweet spot, I was getting problems with in-the-ear effects which was making the sound - no bullshit - sometimes painful to listen to. My ETF data was also showing heavy comb filtering which I wasn't expecting given the level of absorption I have.
During many abortive experiments with stacking RW3 bales I then tried stacking them up against the rear wall to increase the depth there and all of a sudden ....... kaboom!
the treble soundly became the smoothest and most detailed treble I have ever heard. I'm not joking, it is extraordinary and all those in-the-ear effects went instantly. The rather empty and uneven stereo spread suddenly became smooth all the way across and instrument definition was sharper.
Despite the bass problem (room modes), it now sounds bloody damn good with no fatigue at all. The only problem is the treatment to achieve this looks like this:
Those extra 60cm on the back wall look a bit crazy and completely screw up my plan to put a piano there.
My theory on why this works on the treble is that maybe the wooden frame with regular interval vertical supports was causing reflections to build up at frequency multiples. I don't know if that is bollocks or not but there had to have been a reflection problem for my ears to be hurting in the way they were and the comb filtering shown in the ETF results.
Now, please can anyone suggest a way of getting rid of that 60cm block and placing it elsewhere so I can use the rear wall for a piano and have a more regular looking room? Could it also be possible that the plastic wrapping of the RW3 is having a slight diffusing effect on top of the absorption? Would a fabric covering weaken the effect?
I've still got the room modes to sort out but I can negate them slightly with the mixer controls (nothing major - just a mild scoop at 200Hz).
I'm really excited about this again because if I can get the bass working like the treble then I have a really fantastic sounding room.